4-164 Series 90-30/20/Micro Programmable Controllers Reference Manual – September 1998 GFK-0467K
4
SVCREQ #29: Read Elapsed Power Down Time
Use the SVCREQ function #29 to read the the amount of time elapsed between the last power-down
and the most recent power-up. The SVCREQ output is always set to ON, and the output block of
information (see below) starts at the address given in parameter 3 (PARM) of the SVCREQ
function.
Note
This function is available only in the 331 or higher CPUs.
This function has an output parameter block only. The parameter block has a length of 3 words.
Power-Down Elapsed Seconds (low order) address
Power-Down Elapsed Seconds (high order) address + 1
100 Microsecond ticks address + 2
The first two words are the power-down elapsed time in seconds. The last word is the remaining
power-down elapsed time in 100 microsecond ticks (which is always 0). Whenever the PLC can
not properly calculate the power down elapsed time, the time will be set to 0. This will happen
when the PLC is powered up with CLR M/T pressed on the HHP. This will also happen if the
watchdog timer times out before power-down.
Example:
In the following example, when input %I0251 is ON, the Elapsed Power-Down Time is placed into
the parameter block, and the output coil (%Q0001) is turned on. The parameter block is located at
%R0050.
| _____
|%I0251 | | %Q0001
|——| |———| SVC_|——————————————————————————————————————————————————————————( )—
| | |
| | REQ |
| | |
| CONST -|FNC |
| +0029 | |
| | |
|%R0050 -|PARM |
| |_____|
|